1. Field of the Invention
The present invention relates to a photometric instrument. For example, it relates to a photometric instrument which photometrically analyzes biopolymer by irradiating the biopolymer with light.
2. Description of the Related Art
Conventionally, there have been proposed methods of observing a configuration of an object, which is placed on a surface of a substrate, by irradiating the object with excitation light. In Japanese Patent Application Publication No. Hei 9-257813 (hereinafter, JP-A 9-257813), for example, there is described an instrument which irradiates a transparent substrate with excitation light emitted from an excitation source, generates evanescent waves on a surface of the substrate by totally reflecting the excitation light inside the substrate, and detects scattered light of the evanescent waves from a specimen on the substrate. In the instrument described in JP-A 9-257813, however, the scattered light is not spectrally separated.
In addition, for example, Japanese Patent Application Publication No. 2005-70031 (hereinafter, JP-A 2005-70031) describes an instrument for spectrally separating fluorescence and scattered light which come from specimen components excited by evanescent waves. In the instrument described in JP-A 2005-70031, however, the specimen components are not fixed on a boundary surface of a flow path.
On the other hand, there is an instrument which, with a plurality of biomolecules being fixed to a surface of a substrate, generates evanescent waves in a given range on the substrate surface as in the case with JP-A 9-257813, and performs imaging of luminescence of the biomolecules excited by the evanescent waves. Although luminescence of biomolecules includes scattered light and fluorescence, fluorescence is observed in general because scattered light of biomolecules is extremely weak. First, non-fluorescent biomolecules are fixed on the substrate, then, reaction solution containing fluorescent molecules is flown onto the substrate, and luminescence from fixation positions of the biomolecules is observed. Thereby, bonding reactions of the biomolecules and the molecules in the reaction solution can be observed. For example, unlabeled single-stranded DNA is fixed on the substrate at the beginning, and a sequence of the fixed DNA can be read by: introducing thereon a reaction solution containing fluorescent-labeled base species respectively labeled with different phosphors; and spectrally separating fluorescence originating from molecule fixation positions while bonding the single-stranded DNA to its complementary bases.